An amateur photographer from Taunton provided the FBI with several clear, high-quality images Thursdasy showing bombing suspects Tamarlan and Dzhokhar Tsarnaev in the Boston Marathon crowd.

“I have a friend with family members in Homeland Security, and the family members immediately passed the first email to the undersecretary,” hobby photographer Bob Leonard said. “Within 20 minutes, the undersecretary said, ‘Great, we’ve got them,’ and passed it on to the Joint Terrorist Taskforce.”

Leonard, who often shoots photos of youth sports and community events, was in Boston on Monday to photograph the marathon, as he has done several times in the past. After the twin bomb blasts unleashed a scene of chaos, Leonard said he soon wondered whether he had captured the culprits in any of his photos.

“I knew I had a chance,” he said.

When the FBI released video footage of the suspects on Thursday, Leonard recognized the buildings in the background and knew he’d been shooting photos in the same area before a pair of explosions killed three and wounded more than 170 on Monday.

“I felt I was too far away, but the minute the video showed they were down that way, I knew I had a chance to be helpful,” he said. “I might have been taking 10 or 15 pictures a minute.”

Leonard’s photographs show the suspects in the crowd near Whiskey’s and the Back Bay Social Club.

Once he narrowed down which photos to examine more closely, Leonard scanned the crowds for the two men, one wearing a white hat and the other wearing a black hat. Once he spotted them, he used photo processing software to enhance the resolution and crop the images.

“I had some great facial clarity on both of them,” he said. “Sometimes they’re looking right at me and probably worrying, ‘he’s got his camera going crazy.’”

He immediately forwarded the photos to the FBI and called the FBI hotline. He then sent them to the friend he said has family connections to the Department of Homeland Security.

Leonard also recalled witnessing the bomb blasts in Boston.

“You knew it wasn’t fireworks or some gas explosion,” he said. “You just knew it was bad.”

He kept shooting pictures as the aftermath unfolded.

“After a minute or two, I said, ‘Well, I’ve paid my life insurance and my kids are in college,’” he said. “So with a photographer’s heart, and not interfering with police or anything, I went walking down the sidewalk to shoot pictures.”